Recently, since the integration of information appliance products, a touch panel device in the market of human-machine interface (HMI) replaces the traditional devices, such as a keyboard and a mouse. Moreover, the progressing of the touch panel devices that people can easily use and operate handily, the touch panel soon spread to apply in many fields, for example, portable telecommunication devices, banking systems, medical registering systems, warehouse security surveillances and publican information guidance systems etc.
According to the different structure of touch panel sensors, the touch panel devices can be categorized in five specific types: a resistive touch panel, a surface acoustic wave (SAW) touch panel, a capacitive touch panel, a infrared touch panel and a electromagnetic inductive touch panel. However, the capacitive touch panel has been widely used in the large-size panel products, and the capacitive touch panel can either be touched with a bare finger or a conductive device, such as a touch pen for touch panel input device, which altered the value of capacitors and calculates the intersection of X axis and Y axis from the measurements of continuous electrical current across the capacitive sensor, then the controller send related responses to the touch panel device.
With reference to FIG. 1, conventional electrode layers of a capacitive touch panel were disposed in matrix. Each of the vertical electrode layers (7) was coupled with a conducting wire (8), and each of the horizontal electrode layers (9) was coupled with the conducting wire (8). In addition, a gap (13) was defined between the vertical electrode layer (7) and the horizontal electrode layer (9) such that the vertical electrode layer (7) and the horizontal electrode layer (9) were not contact to avoid short-circuit.
Refer to FIG. 2, the capacitive touch panel, which includes a substrate (14). From top to bottom, a black matrix (15), an first planarizing layer (overcoat layer) (16), a conductive metal (17), vertical electrode layer (7), a second planarizing (PLN) layer (18), the conductive metal (17), horizontal electrode layer (9), a third PLN layer (19) are disposed on the substrate (14), wherein the capacitive touch panel further includes a shielded layer (190) disposed on the third PLN layer (19) to reduced VCOM voltage electrical interference with the vertical electrode layer (7) and the horizontal electrode layer (9). At last, a color photo-resist layer (191) is located under the shielded layer (190).
However, the vertical electrode layer (7) and the horizontal electrode layer (9) were disposed oppositely to the second PLN layer (18). When the light are passing through the substrate (14), the chromatic aberration caused by refraction of the second PLN layer (18) results in asymmetrical color-balance effect of the touch panel. Moreover, refer to FIG. 1, the gap (13) defined between the vertical electrode layer (7) and the horizontal electrode layer (9) could avoid that the vertical electrode layer (7) and the horizontal electrode layer (9) contact to each other. If the gap (13) is too large, the users may glimpse the gap (13). Thus, more improvement should be made to the apparel of the touch panel.
Furthermore, since the vertical electrode layer (7) and the horizontal electrode layer (9) are disposed oppositely to the second PLN layer (18), and the third PLN layer (19) is required to planarize the touch panel, the third PLN layer (19) made the touch panel thick and that is a challenge for pursued the explicit thin shape of the touch panel.